1). Field of the Invention
This invention relates to an electronic assembly and a method of constructing an electronic assembly.
2). Discussion of Related Art
Integrated circuits are formed on semiconductor wafers, which are then sawed into individual semiconductor chips, also known as microelectronic dies. Each resulting die is then packaged on a package substrate. The package substrate has a number of Ball Grid Array (BGA) solder ball contact formations on an opposing side, which are electronically connected to the integrated circuit through the package substrate. The package is then placed on a circuit board so that the solder balls may be heated to reflow to attach the package to the circuit board.
A heat sink, or a heat spreader, is often attached to the circuit board and thermally connected to the microelectronic die. The heat sink may remove heat from the microelectronic die as well as structurally reinforce the circuit board. The heat sink is attached to the circuit board by metal pins, or heat sink leads, which are soldered to the circuit board.
Because of the heat sinking properties of the heat sink and pins, the solder cannot be melted at the same temperature the solder balls are reflown as heat conducts from the pins into the heat sink. Therefore, the heat sink cannot be attached to the circuit board in the solder reflow oven, which is used to attach the package substrate to the circuit board.